The determination of imidacloprid in tobacco with high performance liquid chromatography was studied. The imidacloprid was extracted from the sample with ethyl acetate, and purified be liquid extraction with 5% Sodium chloride solution and dichloromethane, respectively. The imidacloprid was separated on a ZORBAX Stable Bound (2.1×50 mm, 1.8 m m) column with acetonitrile and 0.01 mol/L ammonium acetate solution as mobile phase at a flow-rate of 1.0 mL/min. The imidacloprid can be separated completely with in 2.5 min. This method was applied to the determination of imidacloprid in tobacco. The relative standard derivation of intra-day variations was 3.6%, and the relative standard derivation of inter-day variations was 4.8%. The standard recoveries were ranged from 88-96%.

A new method for the determination of sugars (rhamnose, xylose, arobinose, fructose,mannose, glucose,sucrose, maltose) in tobacco and sample preparation with high-speed homogenization was established. The sugars were extracted from the samples by high-speed homogenization with 80% methanol solution, and they were analysed by high performance liquid chromatography with evaporative light scattering detector. The 8 sugars were separated on high performance carbohydrate column using an acetonitrile-water (80:20, v/v) at a flow-rate of 2.0 mL/min. This method had been successfully applied to the determination of sugar in tobacco. The mean recoveries are range from 91-104%, and the relative standard deviations are below 3.4%.

An ion chromatographic method for the determination of potassium, sodium, calcium, magnesium and ammonia in tobacco was developed. The potassium, sodium, calcium, magnesium and ammonia were extracted from the samples by high-speed homogenization with 1% hydrochloric acid solution, and they were separated on an Ionpac CS 16 (5×250 mm, 5 mm) cation ion exchange column with 0.03 mol/L methanesulfonic acid as mobile phase. The recoveries of this method were 97.4 - 102.8%, and the relativity standard deviations were 1.8 - 2.6%. This method has been applied to the determination of potassium, sodium, calcium, magnesium and ammonia in tobacco with good results. Copyright CJI.